Fluid-ejecting integrated circuit utilizing electromagnetic displacement

ABSTRACT

A fluid ejecting integrated circuit (IC) includes a nozzle chamber defined by chamber side walls extending from a wafer substrate, and a roof wall provided on the chamber side walls; a fluid ejecting member provided within the nozzle chamber between the roof wall of the nozzle chamber and the wafer substrate; a support formation provided within the nozzle chamber and spaced inwardly away from the chamber side walls, the support formation extending from the wafer substrate to support the fluid ejecting member thereon; a first planar electrode layered to the fluid ejecting member; a second planar electrode layered on the wafer substrate; and a projection provided on the first planar electrode on a side facing the second planar electrode, the projection for contacting the second planar electrode to prevent contact between the first planar electrode and the second planar electrode. The first and second planar electrode establish a potential therebetween to deform the first planar electrode towards the second planar electrode.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. application Ser. No.11/583,826 filed on Oct. 20, 2006, which is a continuation of U.S.application Ser. No. 10/957,718 filed on Oct. 5, 2004, now issued asU.S. Pat. No. 7,140,723, which is a continuation of U.S. applicationSer. No. 10/184,883 filed on Jul. 1, 2002, now issued as U.S. Pat. No.6,820,968, which is a continuation of U.S. application Ser. No.09/113,070 filed Jul. 10, 1998, now issued as U.S. Pat. No. 6,476,863,the entire contents of which are herein incorporated by reference.

The following Australian provisional patent applications are herebyincorporated by cross-reference. For the purposes of location andidentification, US patent applications identified by their US patentapplication serial numbers (USSN) are listed alongside the Australianapplications from which the U.S. patent applications claim the right ofpriority.

US Patent Application Cross-Referenced (Claiming Right Australian ofPriority from Provisional Australian Provisional Patent No. Application)Docket No. PO7991 6,750,901 ART01US PO8505 6,476,863 ART02US PO79886,788,336 ART03US PO9395 6,322,181 ART04US PO8017 6,597,817 ART06USPO8014 6,227,648 ART07US PO8025 6,727,948 ART08US PO8032 6,690,419ART09US PO7999 6,727,951 ART10US PO8030 6,196,541 ART13US PO79976,195,150 ART15US PO7979 6,362,868 ART16US PO7978 6,831,681 ART18USPO7982 6,431,669 ART19US PO7989 6,362,869 ART20US PO8019 6,472,052ART21US PO7980 6,356,715 ART22US PO8018 6,894,694 ART24US PO79386,636,216 ART25US PO8016 6,366,693 ART26US PO8024 6,329,990 ART27USPO7939 6,459,495 ART29US PO8501 6,137,500 ART30US PO8500 6,690,416ART31US PO7987 7,050,143 ART32US PO8022 6,398,328 ART33US PO84977,110,024 ART34US PO8020 6,431,704 ART38US PO8504 6,879,341 ART42USPO8000 6,415,054 ART43US PO7934 6,665,454 ART45US PO7990 6,542,645ART46US PO8499 6,486,886 ART47US PO8502 6,381,361 ART48US PO79816,317,192 ART50US PO7986 6,850,274 ART51US PO8026 6,646,757 ART53USPO8028 6,624,848 ART56US PO9394 6,357,135 ART57US PO9397 6,271,931ART59US PO9398 6,353,772 ART60US PO9399 6,106,147 ART61US PO94006,665,008 ART62US PO9401 6,304,291 ART63US PO9403 6,305,770 ART65USPO9405 6,289,262 ART66US PP0959 6,315,200 ART68US PP1397 6,217,165ART69US PP2370 6,786,420 DOT01US PO8003 6,350,023 Fluid01US PO80056,318,849 Fluid02US PO8066 6,227,652 IJ01US PO8072 6,213,588 IJ02USPO8040 6,213,589 IJ03US PO8071 6,231,163 IJ04US PO8047 6,247,795 IJ05USPO8035 6,394,581 IJ06US PO8044 6,244,691 IJ07US PO8063 6,257,704 IJ08USPO8057 6,416,168 IJ09US PO8056 6,220,694 IJ10US PO8069 6,257,705 IJ11USPO8049 6,247,794 IJ12US PO8036 6,234,610 IJ13US PO8048 6,247,793 IJ14USPO8070 6,264,306 IJ15US PO8067 6,241,342 IJ16US PO8001 6,247,792 IJ17USPO8038 6,264,307 IJ18US PO8033 6,254,220 IJ19US PO8002 6,234,611 IJ20USPO8068 6,302,528 IJ21US PO8062 6,283,582 IJ22US PO8034 6,239,821 IJ23USPO8039 6,338,547 IJ24US PO8041 6,247,796 IJ25US PO8004 6,557,977 IJ26USPO8037 6,390,603 IJ27US PO8043 6,362,843 IJ28US PO8042 6,293,653 IJ29USPO8064 6,312,107 IJ30US PO9389 6,227,653 IJ31US PO9391 6,234,609 IJ32USPP0888 6,238,040 IJ33US PP0891 6,188,415 IJ34US PP0890 6,227,654 IJ35USPP0873 6,209,989 IJ36US PP0993 6,247,791 IJ37US PP0890 6,336,710 IJ38USPP1398 6,217,153 IJ39US PP2592 6,416,167 IJ40US PP2593 6,243,113 IJ41USPP3991 6,283,581 IJ42US PP3987 6,247,790 IJ43US PP3985 6,260,953 IJ44USPP3983 6,267,469 IJ45US PO7935 6,224,780 IJM01US PO7936 6,235,212IJM02US PO7937 6,280,643 IJM03US PO8061 6,284,147 IJM04US PO80546,214,244 IJM05US PO8065 6,071,750 IJM06US PO8055 6,267,905 IJM07USPO8053 6,251,298 IJM08US PO8078 6,258,285 IJM09US PO7933 6,225,138IJM10US PO7950 6,241,904 IJM11US PO7949 6,299,786 IJM12US PO80606,866,789 IJM13US PO8059 6,231,773 IJM14US PO8073 6,190,931 IJM15USPO8076 6,248,249 IJM16US PO8075 6,290,862 IJM17US PO8079 6,241,906IJM18US PO8050 6,565,762 IJM19US PO8052 6,241,905 IJM20US PO79486,451,216 IJM21US PO7951 6,231,772 IJM22US PO8074 6,274,056 IJM23USPO7941 6,290,861 IJM24US PO8077 6,248,248 IJM25US PO8058 6,306,671IJM26US PO8051 6,331,258 IJM27US PO8045 6,110,754 IJM28US PO79526,294,101 IJM29US PO8046 6,416,679 IJM30US PO9390 6,264,849 IJM31USPO9392 6,254,793 IJM32US PP0889 6,235,211 IJM35US PP0887 6,491,833IJM36US PP0882 6,264,850 IJM37US PP0874 6,258,284 IJM38US PP13966,312,615 IJM39US PP3989 6,228,668 IJM40US PP2591 6,180,427 IJM41USPP3990 6,171,875 IJM42US PP3986 6,267,904 IJM43US PP3984 6,245,247IJM44US PP3982 6,315,914 IJM45US PP0895 6,231,148 IR01US PP08696,293,658 IR04US PP0887 6,614,560 IR05US PP0885 6,238,033 IR06US PP08846,312,070 IR10US PP0886 6,238,111 IR12US PP0877 6,378,970 IR16US PP08786,196,739 IR17US PP0883 6,270,182 IR19US PP0880 6,152,619 IR20US PO80066,087,638 MEMS02US PO8007 6,340,222 MEMS03US PO8010 6,041,600 MEMS05USPO8011 6,299,300 MEMS06US PO7947 6,067,797 MEMS07US PO7944 6,286,935MEMS09US PO7946 6,044,646 MEMS10US PP0894 6,382,769 MEMS13US

FIELD OF THE INVENTION

The present invention relates to fluid dispensing. In particular, thisinvention discloses a micro-electromechanical fluid-dispensing device.

BACKGROUND OF THE INVENTION

This invention is a development of a printing technology that has beendeveloped by the Applicant. This development can be traced byconsidering the referenced patents/patent applications set out above.

Many different types of printing have been invented, a large number ofwhich are presently in use. The known forms of printing have a varietyof methods for marking the print media with a relevant marking media.Commonly used forms of printing include offset printing, laser printingand copying devices, dot matrix type impact printers, thermal paperprinters, film recorders, thermal wax printers, dye sublimation printersand ink jet printers both of the drop on demand and continuous flowtype. Each type of printer has its own advantages and problems whenconsidering cost, speed, quality, reliability, simplicity ofconstruction and operation etc.

In recent years, the field of ink jet printing, wherein each individualpixel of ink is derived from one or more ink nozzles has becomeincreasingly popular primarily due to its inexpensive and versatilenature.

Many different techniques of ink jet printing have been invented. For asurvey of the field, reference is made to an article by J Moore,“Non-Impact Printing: Introduction and Historical Perspective”, OutputHard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).

Ink Jet printers themselves come in many different types. Theutilisation of a continuous stream of ink in ink jet printing appears todate back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hanselldiscloses a simple form of continuous stream electro-static ink jetprinting.

U.S. Pat. No. 3,596,275 by Sweet also discloses a process of continuousink jet printing including the step wherein the ink jet stream ismodulated by a high frequency electro-static field so as to cause dropseparation. This technique is still utilized by several manufacturersincluding Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweetet al)

Piezoelectric ink jet printers are also one form of commonly utilizedink jet printing device. Piezoelectric systems are disclosed by Kyser etal. in U.S. Pat. No. 3,946,398 (1970) which utilises a diaphragm mode ofoperation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses asqueeze mode of operation of a piezoelectric crystal, Stemme in U.S.Pat. No. 3,747,120 (1972) discloses a bend mode of piezo-electricoperation, Howkins in U.S. Pat. No. 4,459,601 discloses a Piezoelectricpush mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No.4,584,590 which discloses a sheer mode type of piezoelectric transducerelement.

Recently, thermal ink jet printing has become an extremely popular formof ink jet printing. The ink jet printing techniques include thosedisclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S.Pat. No. 4,490,728. Both the aforementioned references disclosed ink jetprinting techniques rely upon the activation of an electrothermalactuator which results in the creation of a bubble in a constrictedspace, such as a nozzle, which thereby causes the ejection of ink froman aperture connected to the confined space onto a relevant print media.Manufacturers such as Canon and Hewlett Packard manufacture printingdevices utilising the electro-thermal actuator.

As can be seen in the above referenced matters, Applicant has developedan ink jet printing technology that uses micro-electromechanicalcomponents to achieve the ejection of ink. The use ofmicro-electromechanical components allows printhead chips to have alarge number of densely packed nozzle arrangements without the problemsassociated with heat build-up.

Applicant envisages that this technology can be used to dispense fluid.This invention is therefore intended to be a simple development of thetechnology that has already been the subject of many patent applicationsfiled by the Applicant.

SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, a fluid ejectingintegrated circuit (IC) includes a nozzle chamber defined by chamberside walls extending from a wafer substrate, and a roof wall provided onthe chamber side walls; a fluid ejecting member provided within thenozzle chamber between the roof wall of the nozzle chamber and the wafersubstrate; a support formation provided within the nozzle chamber andspaced inwardly away from the chamber side walls, the support formationextending from the wafer substrate to support the fluid ejecting memberthereon; a first planar electrode layered to the fluid ejecting member;a second planar electrode layered on the wafer substrate; and aprojection provided on the first planar electrode on a side facing thesecond planar electrode, the projection for contacting the second planarelectrode to prevent contact between the first planar electrode and thesecond planar electrode. The first and second planar electrode establisha potential therebetween to deform the first planar electrode towardsthe second planar electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of thepresent invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings, in which:

FIG. 1 is a sectioned side view of one embodiment of a fluid-dispensingchip of the invention, in an operative condition.

FIG. 2 is a sectioned side view of the fluid-dispensing chip of FIG. 1in a quiescent condition.

FIG. 3 is a perspective cross-sectional view of another embodiment ofthe fluid-dispensing chip of the invention.

FIG. 4 is a close-up perspective cross-sectional view (portion A of FIG.3), of the fluid-dispensing chip of FIG. 3.

FIG. 5 is an exploded perspective view illustrating the construction ofthe fluid-dispensing chip of FIG. 3.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In FIGS. 1 and 2, reference numeral 10 generally indicates a sectionedside view of one embodiment of a fluid-dispensing chip of the invention.

The fluid-dispensing chip may include a silicon wafer substrate 12. Adrive circuitry layer 14 is positioned on the wafer substrate 12. Thedrive circuitry layer 14 is in the form of a CMOS two-level metal layerthat includes the drive and control circuitry for the fluid-dispensingchip 10.

A passivation layer 16 of silicon nitride is positioned on the drivecircuitry layer 14 to protect the drive circuitry layer 14. A firstplanar electrode 18 is embedded in the layer 16. The first planarelectrode 18 is of aluminum and is connected to the drive circuitrylayer 14.

The fluid-dispensing chip 10 includes a nozzle chamber wall 19 and aroof wall 20 that define a nozzle chamber 22. The roof wall 20 defines afluid ejection port 44. A fluid-ejecting member 28 is positioned in thenozzle chamber 22. The fluid-ejecting member 28 is planar and is alignedwith and parallel to the first planar electrode 18.

The fluid-ejecting member 28 is positioned on a support formation 34that extends from the passivation layer 16. The support formation 34 isdimensioned so that the fluid-ejecting member 28 is spaced a suitabledistance from the first electrode 18. The support formation 34 isconfigured so that an air gap 40 is encapsulated between thefluid-ejecting member 28 and the first electrode 18.

The fluid-ejecting member 28 includes a second planar electrode 24 thatis positioned in the nozzle chamber 22. The second planar electrode 24is also of aluminum and is also connected to the drive circuitry layer14. The drive circuitry layer 14 is connected to each of the electrodes18, 24 so that a potential can be set up between the electrodes 18, 24so that they are attracted to one another. A layer 26 of silicon nitrideis positioned on the electrode 24 to impart a resilient flexibility tothe fluid-ejecting member 28. Thus, when a potential is set up betweenthe electrodes 18, 24, the fluid-ejecting member 28 is deflected towardsthe first electrode 18, as shown in FIG. 1. When the potential isremoved, the first electrode 18 returns to a quiescent position as shownin FIG. 2.

A layer 32 of polytetrafluoroethylene (PTFE) is positioned on the firstelectrode 18. A layer 36 of PTFE is positioned on the second electrode24, intermediate the electrodes 18, 24. This ensures that the electrodes18, 24 do not stick to one another when the fluid-ejecting member 28 isdeflected towards the first electrode 18. In order further to preventstiction between the electrodes 18, 24, a projection 38 is positioned onthe fluid-ejecting member 28. The projection 38 bears against the layer32 to ensure that there is no contact between the layers 32, 36.

The nozzle chamber wall 19 defines fluid inlet openings 30 that are influid communication with a fluid supply so that the nozzle chamber 22can be supplied with fluid. Fluid flows into a space 41 defined by theroof wall 20, the nozzle chamber wall 19, the fluid-ejecting member 28and the support formation 34. It will be appreciated that this occurswhen the fluid-ejecting member 28 is drawn towards the first electrode18. When the potential is reversed, the fluid-ejecting member 28 isurged away from the first electrode 18 so that a drop 42 of fluid isejected from the fluid ejection port 44. The fluid-ejecting member 28could have sufficient resilience so that a reversal of potential is notnecessary. In this case, release of elastic energy as the fluid-ejectingmember 28 returns to its quiescent condition ensures the ejection of thefluid drop 42.

The roof wall 20 defines a rim 46 about the fluid ejection port 44.

In FIGS. 3 to 5, reference numeral 50 generally indicates anotherembodiment of a fluid-dispensing chip of the invention. With referenceto FIGS. 1 and 2, like reference numerals refer to like parts, unlessotherwise specified.

The fluid-ejecting member 28 has a peripheral portion 52 that ispositioned between the nozzle chamber wall 19 and the layer 26 ofsilicon nitride. A corrugated annular portion 54 is positioned adjacentto the peripheral portion 52. A fluid-ejecting portion 56 defines aremainder of the fluid-ejecting member 28.

The electrodes 18, 24 and their respective PTFE layers 32, 36 aredimensioned to define the air gap 40.

The corrugated portion 54 is configured to expand when the secondelectrode 24 is displaced towards the first electrode 18. The siliconnitride layer 26 imparts a resilient flexibility to the corrugatedportion 54. Thus, the second electrode 24 returns to a quiescentcondition when the electrical potential is removed.

The nozzle chamber wall 19 is shaped to define four radially spacedfluid inlet supply channels 58 that are in fluid communication with thespace 41. These allow fluid to flow into the space 41 when the secondelectrode 24 is drawn towards the first electrode 18.

The nozzle chamber wall 19 defines air spaces 60 that are in fluidcommunication with the air gap 40. These allow the passage of air whenthe second electrode 24 moves towards and away from the first electrode18.

The roof wall 20 has a plurality of etchant openings 62 defined thereinto facilitate the etching of sacrificial material used in thefabrication of the chip 50. The etchant openings 62 are small enough toinhibit the passage of fluid as a result of surface tension effects.

It is important to note that the fluid-dispensing chip 10, 50 isessentially a micro-electromechanical systems (MEMS) device. A methodfor fabricating the device can readily be deduced from the descriptionin referenced application no: U.S. Ser. No. 09/112,787 and in many ofthe other referenced applications.

Applicant envisages that the fluid-dispensing chip 10, 50 will beparticularly suited for lab-on-a-chip applications. It can also beapplied to DNA/RNA arrays, protein chips and sensing and dosing. Thefluid-dispensing chip 10, 50 could also be used for drug deliverysystems.

Numerous variations and/or modifications may be made to the presentinvention as shown in the preferred embodiment without departing fromthe spirit or scope of the invention as broadly described. The preferredembodiment is, therefore, to be considered in all respects to beillustrative and not restrictive.

1. A fluid ejecting integrated circuit (IC), the IC comprising: a nozzlechamber defined by chamber side walls extending from a wafer substrate,and a roof wall provided on the chamber side walls; a fluid ejectingmember provided within the nozzle chamber between the roof wall of thenozzle chamber and the wafer substrate; a support formation providedwithin the nozzle chamber and spaced inwardly away from the chamber sidewalls, the support formation extending from the wafer substrate tosupport the fluid ejecting member thereon; a first planar electrodelayered to the fluid ejecting member; a second planar electrode layeredon the wafer substrate; and a projection provided on the first planarelectrode on a side facing the second planar electrode, the projectionfor contacting the second planar electrode to prevent contact betweenthe first planar electrode and the second planar electrode, wherein thefirst and second planar electrode establish a potential therebetween todeform the first planar electrode towards the second planar electrode.2. A fluid ejecting IC as claimed in claim 1, wherein the supportformation is continuous and defines a sealed air chamber between thefirst and second planar electrodes.
 3. A fluid ejecting IC as claimed inclaim 1, wherein the second planar electrode is coated with a plasticlayer on a side facing the first planar electrode.
 4. A fluid ejectingIC as claimed in claim 1, wherein a layer of silicon nitride is providedon the first electrode.
 5. A fluid ejecting IC as claimed in claim 1,wherein the roof wall defines a raised rim defining a fluid ejectionport.
 6. A fluid ejecting IC as claimed in claim 1, further comprising adrive circuitry layer provided on the wafer substrate.
 7. A fluidejecting IC as claimed in claim 1, further comprising a fluid inletopening defined through the chamber side wall, the fluid inlet openingproviding fluid communication into the nozzle chamber.